.px2rem(@name, @px) {
    @{name}: @px / 75 * 1rem;
}
html, body{
    height: 100%;
}
body{
    display: flex;
    flex-direction: column;
    background-image: url(../imgs/chenshi.png);
    background-repeat: no-repeat;
    background-size: 100% 100%;
}
.header{
    display: flex;
    .px2rem(height, 100);
    .px2rem(line-height, 100);    
    color: #0079ff;
    text-align: center; 
    background: #ffffff;
    border-bottom: #b2b2b2 2px solid;
    .left{
        width: 20%;
        display: flex;
        align-items: center;
        justify-content: center;
        img{
            opacity: 0.8;
            .px2rem(padding-right, 10);
        }
        .px2rem(font-size, 32);
    }
    .center{
        flex: 1;
        .px2rem(font-size, 42); 
        color: #000000;
    }
    .right{
        width: 20%;  
    }
} 
.sec{
    flex: 1;
    overflow: auto;
    background: rgba(0,0,0,0.3);
    .dd{
        color: white;
        .px2rem(font-size, 30);
        .px2rem(line-height, 100);
        .sheng{
            padding: 0 5%;
            border-bottom: 1px #ffffff solid;
            background: url("../imgs/chengshi2.png") no-repeat right center;
            background-origin: content-box;
            transition-property: font-size, color;
            transition-duration: .5s;
            &.da{
                font-size: 1.2em;
            }
        }
        .shi{
            display: none;
            background: rgba(255, 255, 255, 0.2);
            li{
                border-bottom: 1px #ffffff solid;
                padding-left: 5%;
                text-indent: 2em;
            }
        }
    }
}
.btn{
    .px2rem(height, 80);
    .px2rem(line-height, 80);
    text-align: center;
    background: #cccccc;
    color: white;
    opacity: 0.8;
}











